Doesn't work for keys that don't send keysyms by default but instead act as e.g. media keys if you're not holding a modifier. (Media keys are their own USB HID

Doesn't work for keys that don't send keysyms by default but instead act as e.g. media keys if you're not holding a modifier. (Media keys are their own USB HID usage page; the OS keyboard driver doesn't see them.)